Airworthiness Directives; McDonnell Douglas Model DC-9-31 Airplane

This amendment adopts a new airworthiness directive (AD) that is applicable to one McDonnell Douglas Model DC-9-31 airplane. This action requires an inspection to determine if a certain alternating current (AC) cross-tie relay is installed; replacement of a certain AC cross-tie relay with a new AC cross-tie relay; and repetitive cleaning, inspection, repair, and testing of a certain AC cross-tie relay. This action is necessary to prevent AC cross-tie relay failures, which could result in internal arcing of the relay and smoke and/or fire in the cockpit and cabin. This action is intended to address the identified unsafe condition.